Olfactory testing differentiates between progressive supranuclear palsy and idiopathic Parkinson's disease

Abstract

Olfactory dysfunction occurs in most patients with idiopathic Parkinson's disease (PD). In this study, we sought to determine whether such dysfunction is also present in progressive supranuclear palsy (PSP), a condition which shares a number of motor symptoms with PD and is commonly misdiagnosed as PD. We administered the University of Pennsylvania Smell Identification Test, a standardized test of odor identification ability, to 21 PSP patients; 17 also received a forced-choice odor detection threshold test. We compared the olfactory test scores to those obtained from PD patients and normal controls matched to the PSP patients on the basis of age, sex, and smoking habits. Overall, the olfactory function of the PSP patients was markedly superior to that of the PD patients and did not differ significantly from that of the normal controls. There was no association in either the PSP or PD patient groups between (1) the olfactory test scores and (2) measures of motor symptom severity, disease stage, and medication usage. These findings demonstrate that patients with PSP and PD differ markedly in their ability to smell and suggest that olfactory testing may be useful in their differential diagnosis.

Combinations of Markers Provide Clues to the Underlying Neurodegenerative Disorder in REM Sleep Behavior Disorder

“…The deficit in olfaction in PD contrasts with previous reports of preserved or only mildly reduced olfaction in patients with atypical parkinsonism such as a tauopathy or multiple system atrophy (MSA) (Doty et al, 1993;Wenning et al, 1995). In dementia patients, neuropathologic studies reported neuronal alterations in several subcortical structures such as the olfactory tract/bulb, anterior olfactory nucleus, orbito-frontal cortex, hippocampus, and amygdala in the olfactory system (Hubbard et al, 2007).…”

Olfactory dysfunction in LRRK2 G2019S mutation carriers

“…[11][12][13] Loss of neurons and Lewy body deposition are also noted in the anterior olfactory bulb in PD.…”

Improved diagnosis of Parkinson's disease from a detailed olfactory phenotype

“…This can make accurate diagnosis challenging, especially in the early stages of disease 8. Since PSP is not known for specific olfactory pathology, this suggests that the UPSIT test might be used for differential diagnosis of PD versus PSP, as demonstrated previously 16. We offer preliminary support for the possibility that the specific pattern of responses on the test can be used in a similar way to distinguish PD from PSP (AUC = 0.91); however, sample size for this particular comparison is limited in our dataset and so this result should be considered speculative.…”